ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Technical Specification
Satellite Earth Stations and Systems (SES);
Satellite Component of UMTS/IMT-2000;
Part 4: Physical layer procedures;
Sub-part 1: G-family (S-UMTS-G 25.214)
2
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Reference
RTS/SES-00298-4-1
Keywords
interface, MES, MSS, radio, satellite, UMTS
ETSI
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3
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Contents
Intellectual Property Rights ................................................................................................................................5
Foreword.............................................................................................................................................................5
Introduction ........................................................................................................................................................5
1
Scope ........................................................................................................................................................7
2
References ................................................................................................................................................7
2.1
2.2
3
3.1
3.2
4
4.1
4.2
4.2.1
4.2.2
4.3
4.3.1
4.3.1.1
4.3.1.2
4.3.1.3
4.3.2
4.3.2.1
4.3.2.2
4.3.2.3
4.3.2.4
4.3.3
4.3.3.1
4.3.3.2
4.3.4
5
Normative references .........................................................................................................................................7
Informative references........................................................................................................................................8
Definitions and abbreviations...................................................................................................................8
Definitions..........................................................................................................................................................8
Abbreviations .....................................................................................................................................................8
Synchronization procedures .....................................................................................................................9
Spot search .........................................................................................................................................................9
Common physical channel synchronization .......................................................................................................9
P-CCPCH radio frame timing.......................................................................................................................9
S-CCPCH soft combining timing .................................................................................................................9
DPCCH/DPDCH synchronization....................................................................................................................10
Synchronization primitives .........................................................................................................................10
General ..................................................................................................................................................10
Downlink synchronization primitives ...................................................................................................10
Uplink synchronization primitives ........................................................................................................11
Radio link establishment and physical layer reconfiguration for dedicated channels.................................11
General ..................................................................................................................................................11
Satellite gateway radio link set state machine.......................................................................................11
Synchronization procedure A................................................................................................................12
Synchronization procedure B ................................................................................................................13
Radio link monitoring.................................................................................................................................13
Downlink radio link failure ...................................................................................................................13
Uplink radio link failure/restore............................................................................................................13
Transmission timing adjustments ...............................................................................................................14
Power control .........................................................................................................................................14
5.1
Uplink power control........................................................................................................................................14
5.1.1
PRACH .......................................................................................................................................................14
5.1.1.1
General ..................................................................................................................................................14
5.1.1.2
Setting of PRACH control and data part power difference ...................................................................14
5.1.2
DPCCH/DPDCH ........................................................................................................................................14
5.1.2.1
General ..................................................................................................................................................14
5.1.2.2
Ordinary transmit power control ...........................................................................................................15
5.1.2.2.1
General ............................................................................................................................................15
5.1.2.2.2
Algorithm 1 for processing TPC commands ...................................................................................16
5.1.2.2.3
Algorithm 2 for processing TPC commands ...................................................................................17
5.1.2.3
Transmit power control in compressed mode .......................................................................................18
5.1.2.4
Transmit power control in the uplink DPCCH power control preamble...............................................20
5.1.2.5
Setting of the uplink DPCCH/DPDCH power difference .....................................................................21
5.1.2.5.1
General ............................................................................................................................................21
5.1.2.5.2
Signalled gain factors ......................................................................................................................21
5.1.2.5.3
Computed gain factors.....................................................................................................................21
5.1.2.5.4
Setting of the uplink DPCCH/DPDCH power difference in compressed mode ..............................22
5.1.2.6
Maximum and minimum power limits..................................................................................................22
5.2
Downlink power control...................................................................................................................................23
5.2.1
DPCCH/DPDCH ........................................................................................................................................23
5.2.1.1
General ..................................................................................................................................................23
5.2.1.2
Ordinary transmit power control ...........................................................................................................23
5.2.1.2.1
UE behaviour...................................................................................................................................23
ETSI
4
5.2.1.2.2
5.2.1.3
5.2.1.4
5.2.1.4.1
5.2.1.4.2
5.2.1.4.3
5.2.1.4.4
5.2.1.4.5
5.2.1.5
5.2.2
5.2.3
5.2.4
5.2.5
6
6.1
6.1.1
6.1.2
USRAN behaviour...........................................................................................................................24
Power control in compressed mode ......................................................................................................25
Spot selection diversity transmit power control ....................................................................................26
General ............................................................................................................................................26
TPC procedure in UE ......................................................................................................................27
Selection of primary spot.................................................................................................................27
Delivery of primary spot ID ............................................................................................................27
TPC procedure in the network.........................................................................................................28
Open Loop power control .....................................................................................................................29
AICH ..........................................................................................................................................................29
PICH ...........................................................................................................................................................29
S-CCPCH....................................................................................................................................................29
MICH..........................................................................................................................................................29
Random access procedure ......................................................................................................................29
Physical random access procedure ...................................................................................................................29
RACH sub-channels ...................................................................................................................................31
RACH access slot sets ................................................................................................................................31
Annex A (informative):
A.1
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Power control .................................................................................................32
Downlink power control timing .............................................................................................................32
Annex B (informative):
Spot search procedure ...................................................................................33
Annex C (informative):
Bibliography...................................................................................................34
History ..............................................................................................................................................................35
ETSI
5
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Intellectual Property Rights
IPRs essential or potentially essential to the present document may have been declared to ETSI. The information
pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found
in ETSI SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in
respect of ETSI standards", which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web
server (http://webapp.etsi.org/IPR/home.asp).
Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee
can be given as to the existence of other IPRs not referenced in ETSI SR 000 314 (or the updates on the ETSI Web
server) which are, or may be, or may become, essential to the present document.
Foreword
This Technical Specification (TS) has been produced by ETSI Technical Committee Satellite Earth Stations and
Systems (SES).
The present document is specifying the Satellite Radio Interface referenced as SRI Family G at ITU-R, in the frame of
the modification of ITU-R Recommendation M.1457 [13]. This modification has been approved at SG8 meeting in
November 2005.
The present document is part 4, sub-part 1 of a multi-part deliverable covering Satellite Earth Stations and Systems
(SES); Satellite Component of UMTS/IMT-2000; G-family, as identified below:
Part 1:
"Physical channels and mapping of transport channels into physical channels";
Part 2:
"Multiplexing and channel coding";
Part 3:
"Spreading and modulation";
Part 4:
"Physical layer procedures";
Sub-part 1:
"G-family (S-UMTS-G 25.214)";
Sub-part 2:
"A-family (S-UMTS-A 25.214)";
Part 5:
"UE Radio Transmission and Reception";
Part 6:
"Ground stations and space segment radio transmission and reception".
Introduction
S-UMTS stands for the Satellite component of the Universal Mobile Telecommunication System. S-UMTS systems will
complement the terrestrial UMTS (T-UMTS) and inter-work with other IMT-2000 family members through the UMTS
core network. S-UMTS will be used to deliver 3rd generation Mobile Satellite Services (MSS) utilizing either low
(LEO) or medium (MEO) earth orbiting, or geostationary (GEO) satellite(s). S-UMTS systems are based on terrestrial
3GPP specifications and will support access to GSM/UMTS core networks.
NOTE 1: The term T-UMTS will be used in the present document to further differentiate the Terrestrial UMTS
component.
Due to the differences between terrestrial and satellite channel characteristics, some modifications to the terrestrial
UMTS (T-UMTS) standards are necessary. Some specifications are directly applicable, whereas others are applicable
with modifications. Similarly, some T-UMTS specifications do not apply, whilst some S-UMTS specifications have no
corresponding T-UMTS specification.
ETSI
6
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Since S-UMTS is derived from T-UMTS, the organization of the S-UMTS specifications closely follows the original
3rd Generation Partnership Project (3GPP) structure. The S-UMTS numbers have been designed to correspond to the
3GPP terrestrial UMTS numbering system. All S-UMTS specifications are allocated a unique S-UMTS number as
follows:
S-UMTS-n xx.yyy
Where:
•
The numbers xx and yyy correspond to the 3GPP-numbering scheme.
•
n (n = A, B, C, etc.) denotes the family of S-UMTS specifications.
An S-UMTS system is defined by the combination of a family of S-UMTS specifications and 3GPP specifications, as
follows:
•
If an S-UMTS specification exists it takes precedence over the corresponding 3GPP specification (if any). This
precedence rule applies to any references in the corresponding 3GPP specifications.
NOTE 2: Any references to 3GPP specifications within the S-UMTS specifications are not subject to this
precedence rule.
EXAMPLE:
•
An S-UMTS specification may contain specific references to the corresponding 3GPP
specification.
If an S-UMTS specification does not exist, the corresponding 3GPP specification may or may not apply. The
exact applicability of the complete list of 3GPP specifications shall be defined at a later stage.
ETSI
7
1
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Scope
The present document specifies the characteristics of the physical layer procedures used for family G of the satellite
component of UMTS (S-UMTS-G).
It is based on the FDD mode of UTRA defined by TS 125 211 [4], TS 125 212 [9], TS 125 213 [10], TS 125 215 [11],
TS 125 214 [5], TS 125 331 [12] and TS 125 433 [6] and adapted for operation over satellite transponders.
2
References
References are either specific (identified by date of publication and/or edition number or version number) or
non-specific.
•
For a specific reference, subsequent revisions do not apply.
•
Non-specific reference may be made only to a complete document or a part thereof and only in the following
cases:
-
if it is accepted that it will be possible to use all future changes of the referenced document for the
purposes of the referring document;
-
for informative references.
Referenced documents which are not found to be publicly available in the expected location might be found at
http://docbox.etsi.org/Reference.
For online referenced documents, information sufficient to identify and locate the source shall be provided. Preferably,
the primary source of the referenced document should be cited, in order to ensure traceability. Furthermore, the
reference should, as far as possible, remain valid for the expected life of the document. The reference shall include the
method of access to the referenced document and the full network address, with the same punctuation and use of upper
case and lower case letters.
NOTE:
2.1
While any hyperlinks included in this clause were valid at the time of publication ETSI cannot guarantee
their long term validity.
Normative references
The following referenced documents are indispensable for the application of the present document. For dated
references, only the edition cited applies. For non-specific references, the latest edition of the referenced document
(including any amendments) applies.
[1]
ETSI TS 101 851-1-1: "Satellite Earth Stations and Systems (SES); Satellite Component of
UMTS/IMT-2000; Part 1: Physical channels and mapping of transport channels into physical
channels; Sub-part 1: G-family (S-UMTS-G 25.211)".
[2]
ETSI TS 101 851-2-1: "Satellite Earth Stations and Systems (SES); Satellite Component of
UMTS/IMT-2000; Part 2: Multiplexing and channel coding; Sub-part 1: G-family
(S-UMTS-G 25.212)".
[3]
ETSI TS 101 851-3-1: "Satellite Earth Stations and Systems (SES); Satellite Component of
UMTS/IMT-2000; Part 3: Spreading and modulation; Sub-part 1: G-family (S-UMTS-G 25.213)".
[4]
ETSI TS 125 211: "Universal Mobile Telecommunications System (UMTS); Physical channels
and mapping of transport channels onto physical channels (FDD) (3GPP TS 25.211)".
[5]
ETSI TS 125 214: "Universal Mobile Telecommunications System (UMTS); Physical layer
procedures (FDD) (3GPP TS 25.214)".
[6]
ETSI TS 125 433: "Universal Mobile Telecommunications System (UMTS); UTRAN Iub
interface Node B Application Part (NBAP) signalling (3GPP TS 25.433)".
ETSI
8
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
[7]
ETSI TS 125 101: "Universal Mobile Telecommunications System (UMTS); User Equipment
(UE) radio transmission and reception (FDD) (3GPP TS 25.101)".
[8]
ETSI TS 125 133: "Universal Mobile Telecommunications System (UMTS); Requirements for
support of radio resource management (FDD) (3GPP TS 25.133)".
2.2
Informative references
[9]
ETSI TS 125 212: "Universal Mobile Telecommunications System (UMTS); Multiplexing and
channel coding (FDD) (3GPP TS 25.212)".
[10]
ETSI TS 125 213: "Universal Mobile Telecommunications System (UMTS); Spreading and
modulation (FDD) (3GPP TS 25.213)".
[11]
ETSI TS 125 215: "Universal Mobile Telecommunications System (UMTS); Physical layer;
Measurements (FDD) (3GPP TS 25.215)".
[12]
ETSI TS 125 331: "Universal Mobile Telecommunications System (UMTS); Radio Resource
Control (RRC); Protocol specification (3GPP TS 25.331)".
[13]
ITU-R Recommendation M.1457 (2006): "Detailed specifications of the radio interfaces of
International Mobile Telecommunications-2000 (IMT-2000)".
3
Definitions and abbreviations
3.1
Definitions
For the purposes of the present document, the following terms and definitions apply:
L1 combining period: interval of contiguous radio frames when S-CCPCH clusters may be soft combined
S-CCPCH cluster: one or more S-CCPCHs on different RLs, all containing identical physical channel bits
NOTE:
3.2
S-CCPCHs in an S-CCPCH cluster are synchronized such that the delay between the earliest and latest
arriving S-CCPCH at the UE is no more than 296 chips.
Abbreviations
For the purposes of the present document, the following abbreviations apply:
AICH
ASC
BCH
CCPCH
CCTrCH
CPICH
CRC
DL
DPCCH
DPCH
DPDCH
DTX
GEO
LEO
MEO
MICH
MSS
PCA
P-CCPCH
Acquisition Indicator CHannel
Access Service Class
Broadcast CHannel
Common Control Physical CHannel
Coded Composite Transport CHannel
Common PIlot CHannel
Cyclic Redundancy Check
DownLink
Dedicated Physical Control CHannel
Dedicated Physical CHannel
Dedicated Physical Data CHannel
Discontinuous Transmission
Geostationary Earth Orbit
Low Earth Orbit
Medium Earth Orbit
MBMS Indicator CHannel
Mobile Satellite Services
Power Control Algorithm
Primary Common Control Physical CHannel
ETSI
9
P-CPICH
PICH
PRACH
RACH
RAT
RL
RPL
RSCP
S-CCPCH
SCH
SFN
SIR
SSDT
TFC
TFCI
TPC
TTI
UE
UL
USRAN
UTRA
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Primary Common PIlot CHannel
Paging Indicator CHannel
Physical Random Access CHannel
Random Access CHannel
Radio Access Technology
Radio Link
Recovery Period Length
Received Signal Code Power
Secondary Common Control Physical CHannel
Synchronization CHannel
System Frame Number
Signal-to-Interference Ratio
Site Selection Diversity TPC
Transport Format Combination
Transport Frame Combination Indicator
Transmit Power Control
Transmission Time Interval
User Equipment
UpLink
UMTS Satellite Radio Access Network
UMTS Terrestrial Radio Access
4
Synchronization procedures
4.1
Spot search
During the spot search, the UE searches for a satellite beam and determines the downlink scrambling code and common
channel frame synchronization of that satellite beam. How spot search is typically done is described in annex B.
4.2
Common physical channel synchronization
The radio frame timing of all common physical channels can be determined after spot search.
4.2.1
P-CCPCH radio frame timing
The P-CCPCH radio frame timing is found during spot search and the radio frame timing of all common physical
channel are related to that timing as described in TS 101 851-1-1 [1].
4.2.2
S-CCPCH soft combining timing
Higher layers will provide additional timing information when S-CCPCH clusters can be soft combined. The timing
information allows the UE to determine the L1 combining period that applies to each S-CCPCH cluster. The
information also identifies the S-CCPCHs and the RLs in each cluster as well as which S-CCPCH clusters can be soft
combined. The set of S-CCPCH clusters that can be combined does not change during an L1 combining period. When
S-CCPCH clusters can be soft combined, all S-CCPCHs in the clusters shall contain identical bits in their data fields,
although the TFCI fields of S-CCPCH in different clusters may be different. (TFC detection when S-CCPCH clusters
may be soft combined is discussed in TS 101 851-2-1 [2].) An L1 combining period shall contain only complete TTIs.
The maximum delay between S-CCPCH clusters that the UE may combine is set by UE performance requirements.
ETSI
10
4.3
DPCCH/DPDCH synchronization
4.3.1
Synchronization primitives
4.3.1.1
General
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
For the dedicated channels, synchronization primitives are used to indicate the synchronization status of radio links,
both in uplink and downlink. The definition of the primitives is given in the following clauses.
4.3.1.2
Downlink synchronization primitives
Layer 1 in the UE shall every radio frame check synchronization status of the downlink dedicated channels.
Synchronization status is indicated to higher layers using the CPHY-Sync-IND and CPHY-Out-of-Sync-IND
primitives.
The criteria for reporting synchronization status are defined in two different phases.
The first phase starts when higher layers initiate physical dedicated channel establishment (as described in
TS 125 331 [12]) or whenever the UE initiates synchronization procedure A (as described in clause 4.3.2.1) and lasts
until 160 ms after the downlink dedicated channel is considered established by higher layers (physical channel
establishment is defined in TS 125 331 [12]). During this time out-of-sync shall not be reported and in-sync shall be
reported using the CPHY-Sync-IND primitive if the following criterion is fulfilled:
-
The UE estimates the DPCCH quality over the previous 40 ms period to be better than a threshold Qin. This
criterion shall be assumed not to be fulfilled before 40 ms of DPCCH quality measurements have been
collected. Qin is defined implicitly by the relevant tests in TS 125 101 [7].
The second phase starts 160 ms after the downlink dedicated channel is considered established by higher layers. During
this phase both out-of-sync and in-sync are reported as follows.
Out-of-sync shall be reported using the CPHY-Out-of-Sync-IND primitive if any of the following criteria is fulfilled:
-
The UE estimates the DPCCH quality over the previous 160 ms period to be worse than a threshold Qout.
Qout is defined implicitly by the relevant tests in TS 125 101 [7].
-
The 20 most recently received transport blocks with a non-zero length CRC attached, as observed on all
TrCHs using non-zero length CRC, have been received with incorrect CRC. In addition, over the previous
160 ms, all transport blocks with a non-zero length CRC attached have been received with incorrect CRC. In
case no TFCI is used this criterion shall not be considered for the TrCH(s) not using guided detection if they
do not use a non-zero length CRC in all transport formats. If no transport blocks with a non-zero length CRC
attached are received over the previous 160 ms this criterion shall not be assumed to be fulfilled.
In-sync shall be reported using the CPHY-Sync-IND primitive if both of the following criteria are fulfilled:
-
The UE estimates the DPCCH quality over the previous 160 ms period to be better than a threshold Qin.
Qin is defined implicitly by the relevant tests in TS 125 101 [7].
-
At least one transport block with a non-zero length CRC attached, as observed on all TrCHs using non-zero
length CRC, is received in a TTI ending in the current frame with correct CRC. If no transport blocks are
received, or no transport block has a non-zero length CRC attached in a TTI ending in the current frame and in
addition over the previous 160 ms at least one transport block with a non-zero length CRC attached has been
received with a correct CRC, this criterion shall be assumed to be fulfilled. If no transport blocks with a nonzero length CRC attached are received over the previous 160 ms this criterion shall also be assumed to be
fulfilled. In case no TFCI is used this criterion shall not be considered for the TrCH(s) not using guided
detection if they do not use a non-zero length CRC in all transport formats.
How the primitives are used by higher layers is described in TS 125 331 [12]. The above definitions may lead to radio
frames where neither the in-sync nor the out-of-sync primitives are reported.
ETSI
11
4.3.1.3
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Uplink synchronization primitives
Layer 1 in the satellite gateway shall every radio frame check synchronization status of all radio link sets.
Synchronization status is indicated to the RL Failure/Restored triggering function using either the CPHY-Sync-IND or
CPHY-Out-of-Sync-IND primitive. Hence, only one synchronization status indication shall be given per radio link set.
The exact criteria for indicating in-sync/out-of-sync is not subject to specification, but could e.g. be based on received
DPCCH quality or CRC checks. One example would be to have the same criteria as for the downlink synchronization
status primitives.
4.3.2
Radio link establishment and physical layer reconfiguration for
dedicated channels
4.3.2.1
General
Two synchronization procedures are defined in order to obtain physical layer synchronization of dedicated channels
between UE and USRAN:
-
-
Synchronization procedure A: This procedure shall be used when at least one downlink dedicated physical
channel and one uplink dedicated physical channel are to be set up on a frequency and none of the radio links
after the establishment/reconfiguration existed prior to the establishment/reconfiguration which also includes
the following cases:
-
the UE was previously on another RAT i.e. inter-RAT handover;
-
the UE was previously on another frequency i.e. inter-frequency hard handover;
-
the UE has all its previous radio links removed and replaced by other radio links
i.e. intra-frequency hard-handover;
-
after it fails to complete an inter-RAT, intra- or inter-frequency hard-handover TS 125 133 [8], the UE
attempts to re-establish TS 125 331 [12] all the dedicated physical channels which were already
established immediately before the hard-handover attempt. In this case only steps c) and d) of
synchronization procedure A are applicable.
Synchronization procedure B: This procedure shall be used when one or several radio links are added to the
active set and at least one of the radio links prior to the establishment/reconfiguration still exists after the
establishment/reconfiguration.
For existing radio links, the reconfiguration of downlink phase reference from P-CPICH or S-CPICH to dedicated pilots
is not supported. For all other physical layer reconfigurations not listed above, the UE and USRAN shall not perform
any of the synchronization procedures listed above.
The two synchronization procedures are described in clauses 4.3.2.3 and 4.3.2.4 respectively.
4.3.2.2
Satellite gateway radio link set state machine
In the satellite gateway, each radio link set can be in three different states: initial state, out-of-sync state and in-sync
state. Transitions between the different states are shown in figure 1. The state of the satellite gateway at the start of
radio link establishment is described in the following clauses. Transitions between initial state and in-sync state are
described in clauses 4.3.2.3 and 4.3.2.4 and transitions between the in-sync and out-of-sync states are described in
clause 4.3.3.2.
ETSI
12
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Initial
state
RL Restore
RL Failure
In-sync
state
Out-of-sync
state
RL Restore
Figure 1: Satellite gateway radio link set states and transitions
4.3.2.3
Synchronization procedure A
The synchronization establishment procedure, which begins at the time indicated by higher layers (either immediately at
receipt of upper layer signalling, or at an indicated activation time), is as follows:
a)
Each satellite gateway involved in the procedure sets all the radio link sets which are to be set-up for this UE
in the initial state.
b)
USRAN shall start the transmission of the downlink DPCCH and may start the transmission of DPDCH if any
data is to be transmitted. The initial downlink DPCCH transmit power is set by higher layers TS 125 433 [6].
Downlink TPC commands are generated as described in clause 5.1.2.2.1.2.
c)
The UE establishes downlink chip and frame synchronization of DPCCH, using the P-CCPCH timing and
timing offset information notified from USRAN. Frame synchronization can be confirmed using the frame
synchronization word. Downlink synchronization status is reported to higher layers every radio frame
according to clause 4.3.1.2.
d)
The UE shall not transmit on uplink until higher layers consider the downlink physical channel established. If
no activation time for uplink DPCCH has been signalled to the UE or if the UE attempts to re-establish the
DPCH after an inter-RAT, intra- or inter-frequency hard-handover failure TS 125 331 [12], uplink DPCCH
transmission shall start when higher layers consider the downlink physical channel established. If an activation
time has been given, uplink DPCCH transmission shall not start before the downlink physical channel has
been established and the activation time has been reached. Physical channel establishment and activation time
are defined in TS 125 331 [12]. The initial uplink DPCCH transmit power is set by higher layers
TS 125 331 [12]. In case the UE attempts to re-establish the DPCH after an inter-RAT, intra- or
inter-frequency hard-handover failure TS 125 331 [12] the initial uplink DPCCH power shall be the same as
the one used immediately preceding the inter-RAT, intra- or inter-frequency hard-handover attempt. In case of
physical layer reconfiguration the uplink DPCCH power is kept unchanged between before and after the
reconfiguration except for inner loop power control adjustments. A power control preamble shall be applied as
indicated by higher layers. The transmission of the uplink DPCCH power control preamble shall start Npcp
radio frames prior to the start of uplink DPDCH transmission, where Npcp is a higher layer parameter set by
USRAN TS 125 331 [12]; in case the UE attempts to re-establish the DPCH after an inter-RAT, intra- or
inter-frequency hard-handover failure TS 125 331 [12] the UE shall use the value of Npcp as specified in
TS 125 331 [12] for this case. Note that the transmission start delay between DPCCH and DPDCH may be
cancelled using a power control preamble of 0 length. The starting time for transmission of DPDCHs shall also
satisfy the constraints on adding transport channels to a CCTrCH, as defined in TS 101 851-2-1 [2],
independently of whether there are any bits mapped to the DPDCHs. During the uplink DPCCH power control
preamble, independently of the selected TFC, no transmission is done on the DPDCH.
e)
USRAN establishes uplink chip and frame synchronization. Frame synchronization can be confirmed using the
frame synchronization word. Radio link sets remain in the initial state until N_INSYNC_IND successive
in-sync indications are received from layer 1, when the satellite gateway shall trigger the RL Restore
procedure indicating which radio link set has obtained synchronization. When RL Restore has been triggered
the radio link set shall be considered to be in the in-sync state. The parameter value of N_INSYNC_IND is
configurable, see TS 125 433 [6]. The RL Restore procedure may be triggered several times, indicating when
synchronization is obtained for different radio link sets.
ETSI
13
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
The total signalling response delay for the establishment of a new DPCH shall not exceed the requirements
given in TS 125 331 [12].
4.3.2.4
Synchronization procedure B
The synchronization procedure B, which begins at the time indicated by higher layers (either immediately at receipt of
upper layer signalling, or at an indicated activation time) is as follows:
a)
The following applies to each satellite gateway involved in the procedure:
-
New radio link sets are set up to be in initial state.
-
If one or several radio links are added to an existing radio link set, this radio link set shall be considered
to be in the state the radio link set was prior to the addition of the radio link, i.e. if the radio link set was
in the in-sync state before the addition of the radio link it shall remain in that state.
b)
USRAN starts the transmission of the downlink DPCCH/DPDCH for each new radio link at a frame timing
such that the frame timing received at the UE will be within T0 ± 148 chips prior to the frame timing of the
uplink DPCCH/DPDCH at the UE. Simultaneously, USRAN establishes uplink chip and frame
synchronization of each new radio link. Frame synchronization can be confirmed using the frame
synchronization word. Radio link sets considered to be in the initial state shall remain in the initial state until
N_INSYNC_IND successive in-sync indications are received from layer 1, when the satellite gateway shall
trigger the RL Restore procedure indicating which radio link set has obtained synchronization. When RL
Restore is triggered the radio link set shall be considered to be in the in-sync state. The parameter value of
N_INSYNC_IND is configurable, see TS 125 433 [6]. The RL Restore procedure may be triggered several
times, indicating when synchronization is obtained for different radio link sets.
c)
The UE establishes chip and frame synchronization of each new radio link. Layer 1 in the UE keeps reporting
downlink synchronization status to higher layers every radio frame according to the second phase of
clause 4.3.1.2. Frame synchronization can be confirmed using the frame synchronization word.
4.3.3
Radio link monitoring
4.3.3.1
Downlink radio link failure
The downlink radio links shall be monitored by the UE, to trigger radio link failure procedures. The downlink radio link
failure criteria is specified in TS 125 331 [12], and is based on the synchronization status primitives CPHY-Sync-IND
and CPHY-Out-of-Sync-IND, indicating in-sync and out-of-sync respectively.
4.3.3.2
Uplink radio link failure/restore
The uplink radio link sets are monitored by the satellite gateway, to trigger radio link failure/restore procedures. Once
the radio link sets have been established, they will be in the in-sync or out-of-sync states as shown in figure 1 in
clause 4.3.2.2. Transitions between those two states are described below.
The uplink radio link failure/restore criteria are based on the synchronization status primitives CPHY-Sync-IND and
CPHY-Out-of-Sync-IND, indicating in-sync and out-of-sync respectively. Note that only one synchronization status
indication shall be given per radio link set.
When the radio link set is in the in-sync state, the satellite gateway shall start timer T_RLFAILURE after receiving
N_OUTSYNC_IND consecutive out-of-sync indications. the satellite gateway shall stop and reset timer
T_RLFAILURE upon receiving successive N_INSYNC_IND in-sync indications. If T_RLFAILURE expires, the
satellite gateway shall trigger the RL Failure procedure and indicate which radio link set is out-of-sync. When the RL
Failure procedure is triggered, the state of the radio link set change to the out-of-sync state.
When the radio link set is in the out-of-sync state, after receiving N_INSYNC_IND successive in-sync indications the
satellite gateway shall trigger the RL Restore procedure and indicate which radio link set has re-established
synchronization. When the RL Restore procedure is triggered, the state of the radio link set change to the in-sync state.
The specific parameter settings (values of T_RLFAILURE, N_OUTSYNC_IND, and N_INSYNC_IND) are
configurable, see TS 125 433 [6].
ETSI
14
4.3.4
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Transmission timing adjustments
During a connection the UE may adjust its DPDCH/DPCCH transmission time instant.
If the receive timing for any downlink DPCCH/DPDCH in the current active set has drifted, so the time between
reception of the downlink DPCCH/DPDCH in question and transmission of uplink DPCCH/DPDCH lies outside the
valid range, L1 shall inform higher layers of this, so that the network can be informed of this and downlink timing can
be adjusted by the network.
The maximum rate of uplink TX time adjustment, and the valid range for the time between downlink DPCCH/DPDCH
reception and uplink DPCCH/DPDCH transmission in the UE are defined by the requirements specified in
TS 125 133 [8].
5
Power control
5.1
Uplink power control
5.1.1
PRACH
5.1.1.1
General
The power control during the physical random access procedure is described in clause 5.2.5. The setting of power of the
message control and data parts is described in clause 5.1.1.2.
5.1.1.2
Setting of PRACH control and data part power difference
The message part of the uplink PRACH channel shall employ gain factors to control the control/data part relative power
similar to the uplink dedicated physical channels. Hence, clause 5.1.2.5 applies also for the RACH message part, with
the differences that:
-
βc is the gain factor for the control part (similar to DPCCH);
-
βd is the gain factor for the data part (similar to DPDCH);
-
no inner loop power control is performed.
5.1.2
DPCCH/DPDCH
It is not recommended to activate DPCH inner loop power control for geo-stationary constellations. Inner loop power
control may be activated for LEO constellations.
5.1.2.1
General
The initial uplink DPCCH transmit power is set by higher layers. Subsequently the uplink transmit power control
procedure simultaneously controls the power of a DPCCH and its corresponding DPDCHs (if present). The relative
transmit power offset between DPCCH and DPDCHs is determined by the network and is computed according to
clause 5.1.2.5 using the gain factors signalled to the UE using higher layer signalling.
The operation of the inner power control loop, described in clause 5.1.2.2, adjusts the power of the DPCCH and
DPDCHs by the same amount, provided there are no changes in gain factors. Additional adjustments to the power of the
DPCCH associated with the use of compressed mode are described in clause 5.1.2.3.
Any change in the uplink DPCCH transmit power shall take place immediately before the start of the pilot field on the
DPCCH. The change in DPCCH power with respect to its previous value is derived by the UE and is denoted by
ΔDPCCH (in dB). The previous value of DPCCH power shall be that used in the previous slot, except in the event of an
interruption in transmission due to the use of compressed mode, when the previous value shall be that used in the last
slot before the transmission gap.
ETSI
15
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
During the operation of the uplink power control procedure the UE transmit power shall not exceed a maximum
allowed value which is the lower out of the maximum output power of the terminal power class and a value which may
be set by higher layer signalling.
Uplink power control shall be performed while the UE transmit power is below the maximum allowed output power.
The provisions for power control at the maximum allowed value and below the required minimum output power (as
defined in TS 125 101 [7]) are described in clause 5.1.2.6.
5.1.2.2
Ordinary transmit power control
5.1.2.2.1
General
The uplink inner-loop power control adjusts the UE transmit power in order to keep the received uplink
Signal-to-Interference Ratio (SIR) at a given SIR target, SIRtarget.
The serving spots (spots in the active set) should estimate signal-to-interference ratio SIRest of the received uplink
DPCH. The serving spots should then generate TPC commands and transmit the commands once per frame according to
the procedure specified in the present document.
Upon reception of one or more TPC commands in a frame, the UE shall derive a single TPC command, TPC_cmd, for
each frame, combining multiple TPC commands if more than one is received in a frame. This is also valid when SSDT
transmission is used in the downlink. Two algorithms shall be supported by the UE for deriving a TPC_cmd. Which of
these two algorithms is used is determined by a UE-specific higher-layer parameter, "PowerControlAlgorithm", and is
under the control of the USRAN. If "PowerControlAlgorithm" indicates "algorithm1", then the layer 1 parameter PCA
shall take the value 1 and if "PowerControlAlgorithm" indicates "algorithm2" then PCA shall take the value 2.
If PCA has the value 1, Algorithm 1, described in clause 5.1.2.2.2, shall be used for processing TPC commands.
If PCA has the value 2, Algorithm 2, described in clause 5.1.2.2.3, shall be used for processing TPC commands.
The step size ΔTPC is a layer 1 parameter which is derived from the UE-specific higher-layer parameter "TPC-StepSize"
which is under the control of the USRAN. If "TPC-StepSize" has the value "dB1", then the layer 1 parameter ΔTPC shall
take the value 1 dB and if "TPC-StepSize" has the value "dB2", then ΔTPC shall take the value 2 dB. The parameter
"TPC-StepSize" only applies to Algorithm 1 as stated in TS 125 331 [12]. For Algorithm 2 ΔTPC shall always take the
value 1 dB.
After deriving of the combined TPC command TPC_cmd using one of the two supported algorithms, the UE shall
adjust the transmit power with a step of ±Δ1PC or ±Δ2PC dB according to the TPC command. The change of transmitter
power shall apply at the beginning of a new frame.
The relationship between the TPC symbol and the transmitter power control command is presented in table 1.
Table 1: TPC Bit Pattern
TPC Bit Pattern Transmitter power control command
00
Reduce large power step
01
Reduce small power step
10
Increase small power step
11
Increase large power step
5.1.2.2.1.1
Out of synchronization handling
After 160 ms after physical channel establishment (defined in TS 125 331 [12]), the UE shall control its transmitter
according to a downlink DPCCH quality criterion as follows:
-
The UE shall shut its transmitter off when the UE estimates the DPCCH quality over the last 160 ms period to
be worse than a threshold Qout. Qout is defined implicitly by the relevant tests in TS 125 101 [7].
ETSI
16
-
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
The UE can turn its transmitter on again when the UE estimates the DPCCH quality over the last 160 ms
period to be better than a threshold Qin. Qin is defined implicitly by the relevant tests in TS 125 101 [7]. When
transmission is resumed, the power of the DPCCH shall be the same as when the UE transmitter was shut off.
5.1.2.2.1.2
TPC command generation on downlink during RL initialization
When commanded by higher layers the TPC commands sent on a downlink radio link from satellite gateways that have
not yet achieved uplink synchronization shall follow a pattern as follows:
If higher layers indicate by "First RLS indicator" that the radio link is part of the first radio link set sent to the UE and
the value "n" obtained from the parameter "DL TPC pattern 01 count" passed by higher layers is different from 0 then:
-
the TPC pattern shall consist of n instances of the pair of TPC commands ("0","1"), followed by one instance
of TPC command "1", where ("0","1") indicates the TPC commands to be transmitted in 2 consecutive slots;
-
the TPC pattern continuously repeat but shall be forcibly re-started at the beginning of each frame where CFN
mod 4 = 0;
else
-
the TPC pattern shall consist only of TPC commands "1".
The TPC pattern shall terminate once uplink synchronization is achieved.
5.1.2.2.2
5.1.2.2.2.1
Algorithm 1 for processing TPC commands
Derivation of TPC_cmd when only one TPC command is received in each frame
When a UE is not in soft handover, only one TPC command will be received in each frame. In this case, the value of
TPC_cmd shall be derived as follows:
-
If the received TPC command is equal to 0 then TPC_cmd for that frame is -1.
-
If the received TPC command is equal to 1, then TPC_cmd for that frame is 1.
5.1.2.2.2.2
Combining of TPC commands from radio links of the same radio link set
When a UE is in soft handover, multiple TPC commands may be received in each frame from different spots in the
active set. In some cases, the UE has the knowledge that some of the transmitted TPC commands in a frame are the
same. This is the case when the radio links are in the same radio link set. For these cases, the TPC commands from the
same radio link set shall be combined into one TPC command, to be further combined with other TPC commands as
described in clause 5.1.2.2.2.3.
5.1.2.2.2.3
Combining of TPC commands from radio links of different radio link sets
This clause describes the general scheme for combination of the TPC commands from radio links of different radio link
sets.
First, the UE shall conduct a soft symbol decision Wi on each of the power control commands TPCi, where
i = 1, 2, …, N, where N is greater than 1 and is the number of TPC commands from radio links of different radio link
sets, that may be the result of a first phase of combination according to clause 5.1.2.2.2.2.
Finally, the UE derives a combined TPC command, TPC_cmd, as a function γ of all the N soft symbol decisions Wi:
-
TPC_cmd = γ (W1, W2, … WN), where TPC_cmd can take the values 1 or -1.
ETSI
17
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
The function γ shall fulfil the following criteria:
If the N TPCi commands are random and uncorrelated, with equal probability of being transmitted as "0" or "1", the
probability that the output of γ is equal to 1 shall be greater than or equal to 1/(2N), and the probability that the output of
γ is equal to -1 shall be greater than or equal to 0,5. Further, the output of γ shall equal 1 if the TPC commands from all
the radio link sets are reliably "1", and the output of γ shall equal -1 if a TPC command from any of the radio link sets is
reliably "0".
5.1.2.2.3
NOTE:
5.1.2.2.3.1
Algorithm 2 for processing TPC commands
Algorithm 2 makes it possible to emulate smaller step sizes than the minimum power control step
specified in clause 5.1.2.2.1, or to turn off uplink power control by transmitting an alternating series of
TPC commands.
Derivation of TPC_cmd when only one TPC command is received in each frame
When a UE is not in soft handover, only one TPC command will be received in each frame. In this case, the UE shall
process received TPC commands on a 5-frames cycle, where the sets of 5 frames shall be aligned to the frame
boundaries and there shall be no overlap between each set of 5 frames.
The value of TPC_cmd shall be derived as follows:
-
For the first 4 frames of a set, TPC_cmd = 0.
-
For the fifth frame of a set, the UE uses hard decisions on each of the 5 received TPC commands as follows:
-
If all 5 hard decisions within a set are 1 then TPC_cmd = 1 in the 5th frame.
-
If all 5 hard decisions within a set are 0 then TPC_cmd = -1 in the 5th frame.
-
Otherwise, TPC_cmd = 0 in the 5th frame.
5.1.2.2.3.2
Combining of TPC commands from radio links of the same radio link set
When a UE is in soft handover, multiple TPC commands may be received in each frame from different spots in the
active set. In some cases, the UE has the knowledge that some of the transmitted TPC commands in a frame are the
same. This is the case when the radio links are in the same radio link set. For these cases, the TPC commands from
radio links of the same radio link set shall be combined into one TPC command, to be processed and further combined
with any other TPC commands as described in clause 5.1.2.2.2.3.
5.1.2.2.3.3
Combining of TPC commands from radio links of different radio link sets
This clause describes the general scheme for combination of the TPC commands from radio links of different radio link
sets.
The UE shall make a hard decision on the value of each TPCi, where i = 1, 2, …, N and N is the number of TPC
commands from radio links of different radio link sets, that may be the result of a first phase of combination according
to clause 5.1.2.2.3.2.
The UE shall follow this procedure for 5 consecutive frames, resulting in N hard decisions for each of the 5 frames.
The sets of 5 frames shall be aligned to the frame boundaries and there shall be no overlap between each set of
5 frames.
The value of TPC_cmd is zero for the first 4 frames. After 5 frames have elapsed, the UE shall determine the value of
TPC_cmd for the fifth frame in the following way:
The UE first determines one temporary TPC command, TPC_tempi, for each of the N sets of 5 TPC commands as
follows:
-
If all 5 hard decisions within a set are "1", TPC_tempi = 1.
ETSI
18
-
If all 5 hard decisions within a set are "0", TPC_tempi = -1.
-
Otherwise, TPC_tempi = 0.
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Finally, the UE derives a combined TPC command for the fifth frame, TPC_cmd, as a function γ of all the N temporary
power control commands TPC_tempi:
TPC_cmd(5th frame) = γ (TPC_temp1, TPC_temp2, …, TPC_tempN), where TPC_cmd(5th frame) can take the values
1, 0 or -1, and γ is given by the following definition:
-
TPC_cmd is set to -1 if any of TPC_temp1 to TPC_tempN are equal to -1.
-
Otherwise, TPC_cmd is set to 1 if
-
Otherwise, TPC_cmd is set to 0.
5.1.2.3
1
N
N
TPC _ temp i > 0,5 .
∑
i =1
Transmit power control in compressed mode
In compressed mode, one or more transmission gap pattern sequences are active. Therefore some frames are
compressed and contain transmission gaps. The uplink power control procedure is as specified in clause 5.1.2.2, using
the same USRAN supplied parameters for Power Control Algorithm and step size (ΔTPC), but with additional features
which aim to recover as rapidly as possible a signal-to-interference ratio (SIR) close to the target SIR after each
transmission gap.
The serving spots (spots in the active set) should estimate signal-to-interference ratio SIRest of the received uplink
DPCH. The serving spots should then generate TPC commands and transmit the commands once per spot, except
during downlink transmission gaps, according to the following rule: if SIRest > SIRcm_target then the TPC command to
transmit is "0", while if SIRest < SIRcm_target then the TPC command to transmit is "1".
-
SIRcm_target is the target SIR during compressed mode and fulfils;
-
SIRcm_target = SIRtarget + ΔSIRPILOT + ΔSIR1_coding + ΔSIR2_coding,
where ΔSIR1_coding and ΔSIR2_coding are computed from uplink parameters DeltaSIR1, DeltaSIR2, DeltaSIRafter1,
DeltaSIRafter2 signalled by higher layers as:
-
ΔSIR1_coding = DeltaSIR1 if the start of the first transmission gap in the transmission gap pattern is within
the current uplink frame.
-
ΔSIR1_coding = DeltaSIRafter1 if the current uplink frame just follows a frame containing the start of the first
transmission gap in the transmission gap pattern.
-
ΔSIR2_coding = DeltaSIR2 if the start of the second transmission gap in the transmission gap pattern is within
the current uplink frame.
-
ΔSIR2_coding = DeltaSIRafter2 if the current uplink frame just follows a frame containing the start of the
second transmission gap in the transmission gap pattern.
-
ΔSIR1_coding = 0 dB and ΔSIR2_coding = 0 dB in all other cases.
ΔSIRPILOT is defined as: ΔSIRPILOT = 10Log10 (Npilot,N/Npilot,curr_frame),
where Npilot,curr_frame is the number of pilot bits per slot in the current uplink frame, and Npilot,N is the number of pilot
bits per slot in a normal uplink frame without a transmission gap.
In the case of several compressed mode pattern sequences being used simultaneously, ΔSIR1_coding and
ΔSIR2_coding offsets are computed for each compressed mode pattern and all ΔSIR1_coding and ΔSIR2_coding
offsets are summed together.
ETSI
19
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
In compressed mode, compressed frames may occur in either the uplink or the downlink or both. In uplink compressed
frames, the transmission of uplink DPDCH(s) and DPCCH shall both be stopped during transmission gaps.
Due to the transmission gaps in compressed frames, there may be missing TPC commands in the downlink. If no
downlink TPC command is transmitted, the corresponding TPC_cmd derived by the UE shall be set to zero.
Compressed and non-compressed frames in the uplink DPCCH may have a different number of pilot bits per slot. A
change in the transmit power of the uplink DPCCH would be needed in order to compensate for the change in the total
pilot energy. Therefore at the start of each slot the UE shall derive the value of a power offset Δ PILOT. If the number of
pilot bits per slot in the uplink DPCCH is different from its value in the most recently transmitted slot, Δ PILOT (in dB)
shall be given by:
Δ PILOT = 10Log10 (Npilot,prev/Npilot,curr);
where Npilot,prev is the number of pilot bits in the most recently transmitted slot , and Npilot,curr is the number of pilot
bits in the current slot. Otherwise, including during transmission gaps in the downlink, Δ PILOT shall be zero.
Unless otherwise specified, in every slot during compressed mode the UE shall adjust the transmit power of the uplink
DPCCH with a step of ΔDPCCH (in dB) which is given by:
ΔDPCCH = ΔTPC × TPC_cmd + Δ PILOT.
At the start of the first slot after an uplink or downlink transmission gap the UE shall apply a change in the transmit
power of the uplink DPCCH by an amount ΔDPCCH (in dB), with respect to the uplink DPCCH power in the most
recently transmitted uplink slot, where:
ΔDPCCH = Δ RESUME + Δ PILOT.
The value of Δ RESUME (in dB) shall be determined by the UE according to the Initial Transmit Power mode (ITP). The
ITP is a UE specific parameter, which is signalled by the network with the other compressed mode parameters
(see TS 125 215 [11]). The different modes are summarized in table 2.
Table 2: Initial Transmit Power modes during compressed mode
Initial Transmit Power mode
0
1
Description
Δ RESUME = ΔTPC × TPC_cmdgap
Δ RESUME = δ last
In the case of a transmission gap in the uplink, TPC_cmdgap shall be the value of TPC_cmd derived in the first slot of
the uplink transmission gap, if a downlink TPC_command is transmitted in that slot. Otherwise TPC_cmdgap shall be
zero.
δ last shall be equal to the most recently computed value of δi. δi shall be updated according to the following recursive
relations, which shall be executed in all slots in which both the uplink DPCCH and a downlink TPC command are
transmitted, and in the first slot of an uplink transmission gap if a downlink TPC command is transmitted in that slot:
δ i = 0,9375δ i −1 − 0,96875TPC _ cmd i Δ TPC k sc
δ i −1 = δ i
where:
TPC_cmdi is the power control command derived by the UE in that slot;
ksc = 0 if additional scaling is applied in the current slot and the previous slot as described in clause 5.1.2.6
and ksc = 1 otherwise.
ETSI
20
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
δi-1 is the value of δi computed for the previous slot. The value of δi-1 shall be initialized to zero when the uplink
DPCCH is activated, and also at the end of the first slot after each uplink transmission gap, and also at the end of the
first slot after each downlink transmission gap. The value of δi shall be set to zero at the end of the first slot after each
uplink transmission gap.
After a transmission gap in either the uplink or the downlink, the period following resumption of simultaneous uplink
and downlink DPCCH transmission is called a recovery period. RPL is the recovery period length and is expressed as a
number of slots. RPL is equal to the minimum value out of the transmission gap length and 7 slots. If a transmission gap
is scheduled to start before RPL slots have elapsed, then the recovery period shall end at the start of the gap, and the
value of RPL shall be reduced accordingly.
During the recovery period, 2 modes are possible for the power control algorithm. The Recovery Period Power control
mode (RPP) is signalled with the other compressed mode parameters (see TS 125 215 [11]). The different modes are
summarized in table 3.
Table 3: Recovery Period Power control modes during compressed mode
Recovery Period power
control mode
Description
0
Transmit power control is applied using the algorithm determined by the value
of PCA, as in clause 5.1.2.2 with step size ΔTPC.
1
Transmit power control is applied using algorithm 1 (see clause 5.1.2.2.2) with
step size ΔRP-TPC during RPL slots after each transmission gap.
For RPP mode 0, the step size is not changed during the recovery period and ordinary transmit power control is applied
(see clause 5.1.2.2), using the algorithm for processing TPC commands determined by the value of PCA (see
clauses 5.1.2.2.2 and 5.1.2.2.3).
For RPP mode 1, during RPL slots after each transmission gap, power control algorithm 1 is applied with a step size
ΔRP-TPC instead of ΔTPC, regardless of the value of PCA. Therefore, the change in uplink DPCCH transmit power at the
start of each of the RPL + 1 slots immediately following the transmission gap (except for the first slot after the
transmission gap) is given by:
ΔDPCCH = ΔRP-TPC × TPC_cmd + Δ PILOT .
ΔRP-TPC is called the recovery power control step size and is expressed in dB. If PCA has the value 1, ΔRP-TPC is equal
to the minimum value of 3 dB and 2ΔTPC. If PCA has the value 2 , ΔRP-TPC is equal to 1 dB.
After the recovery period, ordinary transmit power control resumes using the algorithm specified by the value of PCA
and with step size ΔTPC.
If PCA has the value 2 , the sets of slots over which the TPC commands are processed shall remain aligned to the frame
boundaries in the compressed frame. For both RPP mode 0 and RPP mode 1, if the transmission gap or the recovery
period results in any incomplete sets of TPC commands, TPC_cmd shall be zero for those sets of slots which are
incomplete.
5.1.2.4
Transmit power control in the uplink DPCCH power control preamble
An uplink DPCCH power control preamble is a period of uplink DPCCH transmission prior to the start of the uplink
DPDCH transmission. The downlink DPCCH shall also be transmitted during an uplink DPCCH power control
preamble.
The length of the uplink DPCCH power control preamble is a higher layer parameter signalled by the network as
defined in TS 125 331 [12]. The uplink DPDCH transmission shall commence after the end of the uplink DPCCH
power control preamble.
During the uplink DPCCH power control preamble the change in uplink DPCCH transmit power shall be given by:
ΔDPCCH = ΔTPC × TPC_cmd.
ETSI
21
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
During the uplink DPCCH power control preamble TPC_cmd is derived according to algorithm 1 as described in
clause 5.1.2.2.1, regardless of the value of PCA.
Ordinary power control (see clause 5.1.2.2), with the power control algorithm determined by the value of PCA and step
size ΔTPC, shall be used after the end of the uplink DPCCH power control preamble.
5.1.2.5
Setting of the uplink DPCCH/DPDCH power difference
5.1.2.5.1
General
The uplink DPCCH and DPDCH(s) are transmitted on different codes as defined in TS 101 851-3-1 [3]. The gain
factors βc and βd may vary for each TFC. There are two ways of controlling the gain factors of the DPCCH code and
the DPDCH codes for different TFCs in normal (non-compressed) frames:
-
βc and βd are signalled for the TFC; or
-
βc and βd is computed for the TFC, based on the signalled settings for a reference TFC.
Combinations of the two above methods may be used to associate βc and βd values to all TFCs in the TFCS. The two
methods are described in clauses 5.1.2.5.2 and 5.1.2.5.3 respectively. Several reference TFCs may be signalled from
higher layers.
The gain factors may vary on radio frame basis depending on the current TFC used. Further, the setting of gain factors
is independent of the inner loop power control.
After applying the gain factors, the UE shall scale the total transmit power of the DPCCH and DPDCH(s), such that the
DPCCH output power follows the changes required by the power control procedure with power adjustments of
ΔDPCCH dB, subject to the provisions of clause 5.1.2.6.
The gain factors during compressed frames are based on the nominal power relation defined in normal frames, as
specified in clause 5.1.2.5.4.
5.1.2.5.2
Signalled gain factors
When the gain factors βc and βd are signalled by higher layers for a certain TFC, the signalled values are used directly
for weighting of DPCCH and DPDCH(s). The variable Aj, called the nominal power relation is then computed as:
Aj =
5.1.2.5.3
βd
βc
.
Computed gain factors
The gain factors βc and βd may also be computed for certain TFCs, based on the signalled settings for a reference TFC.
Let βc,ref and βd,ref denote the signalled gain factors for the reference TFC. Further, let βc,j and βd,j denote the gain
factors used for the j:th TFC. Also let Lref denote the number of DPDCHs used for the reference TFC and L,j denote the
number of DPDCHs used for the j:th TFC.
Define the variable
K ref = ∑ RM i ⋅ N i ;
i
where RMi is the semi-static rate matching attribute for transport channel i (defined in TS 101 851-2-1 [2]), Ni is the
number of bits output from the radio frame segmentation block for transport channel i (defined in TS 101 851-2-1 [2]),
and the sum is taken over all the transport channels i in the reference TFC.
ETSI
22
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Similarly, define the variable
K j = ∑ RM i ⋅ N i ;
i
where the sum is taken over all the transport channels i in the j:th TFC.
The variable Aj, called the nominal power relation is then computed as:
Aj =
β d ,ref
β c,ref
×
L ref
Kj
Lj
K ref
.
The gain factors for the j:th TFC are then computed as follows:
-
If Aj > 1, then β d , j = 1,0 and β c, j is the largest quantized β -value, for which the condition
holds. Since
β c, j
may not be set to zero, if the above rounding results in a zero value,
β c, j
β c, j
≤ 1 / Aj
shall be set to the
lowest quantized amplitude ratio of 1/15 as specified in TS 101 851-3-1 [3].
-
If Aj ≤ 1, then
βd , j
is the smallest quantized β -value, for which the condition
βd , j
≥ Aj holds and
β c, j = 1,0 .
The quantized β-values are defined in TS 101 851-3-1 [3].
5.1.2.5.4
Setting of the uplink DPCCH/DPDCH power difference in compressed mode
The gain factors used during a compressed frame for a certain TFC are calculated from the nominal power relation used
in normal (non-compressed) frames for that TFC. Let Aj denote the nominal power relation for the j:th TFC in a normal
frame. Further, let βc,C,j and βd,C,j denote the gain factors used for the j:th TFC when the frame is compressed. The
variable AC,j is computed as:
AC , j = A j ×
15 × N pilot,C
N slots,C × N pilot , N
;
where Npilot,C is the number of pilot bits per slot when in compressed mode, and Npilot,N is the number of pilot bits per
slot in normal mode. Nslots,C is the number of slots in the compressed frame used for transmitting the data.
The gain factors for the j:th TFC in a compressed frame are computed as follows:
-
If AC,j > 1, then β d ,C , j = 1,0 and
β c,C , j
β c,C , j
-
≤ 1 / AC,j holds. Since
β c,C , j
β c,C , j
is the largest quantized β -value, for which the condition
may not be set to zero, if the above rounding results in a zero value,
shall be set to the lowest quantized amplitude ratio of 1/15 as specified in TS 101 851-3-1 [3].
If AC,j ≤ 1, then
β d ,C , j
is the smallest quantized β -value, for which the condition
β d ,C , j
≥ AC,j holds and
β c,C , j = 1,0 .
The quantized β-values are defined in TS 101 851-3-1 [3].
5.1.2.6
Maximum and minimum power limits
In the case that the total UE transmit power (after applying DPCCH power adjustments and gain factors) would exceed
the maximum allowed value, the UE shall apply additional scaling to the total transmit power so that it is equal to the
maximum allowed power. This additional scaling shall be such that the power ratio between DPCCH and DPDCH
remains as required by clause 5.1.2.5. Any scaling shall only be applied or changed at a DPCCH slot boundary.
ETSI
23
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
When transmitting on a DPCH the UE is not required to be capable of reducing its total transmit power below the
minimum level required in TS 125 101 [7]. However, it may do so, provided that the power ratio between DPCCH and
DPDCH remains as specified in clause 5.1.2.5. Some further regulations also apply as follows: In the case that the total
UE transmit power (after applying DPCCH power adjustments and gain factors) would be at or below the total transmit
power in the previously transmitted slot and also at or below the required minimum power specified in TS 125 101 [7],
the UE may apply additional scaling to the total transmit power, subject to the following restrictions:
-
The total transmit power after applying any additional scaling shall not exceed the required minimum power,
nor the total transmit power in the previously transmitted slot.
-
The magnitude of any reduction in total transmit power between slots after applying any additional scaling
shall not exceed the magnitude of the calculated power reduction before the additional scaling.
In the case that the total UE transmit power in the previously transmitted slot is at or below the required minimum
power specified in TS 125 101 [7] and the DPCCH power adjustment and gain factors for the current slot would result
in an increase in total power, then no additional scaling shall be used (i.e. power control shall operate as normal).
If the UE applies any additional scaling to the total transmit power as described above, this scaling shall be included in
the computation of any DPCCH power adjustments to be applied in the next transmitted slot.
5.2
Downlink power control
The transmit power of the downlink channels is determined by the network. In general the ratio of the transmit power
between different downlink channels is not specified and may change with time. However, regulations exist as
described in the following clauses.
Higher layer power settings shall be interpreted as setting of the total power, i.e. the sum of the power from the two
antennas in case of transmit diversity.
5.2.1
DPCCH/DPDCH
5.2.1.1
General
The downlink transmit power control procedure controls simultaneously the power of a DPCCH and its corresponding
DPDCHs. The power control loop adjusts the power of the DPCCH and DPDCHs with the same amount, i.e. the
relative power difference between the DPCCH and DPDCHs is not changed.
The relative transmit power offset between DPCCH fields and DPDCHs is determined by the network The TFCI, TPC
and pilot fields of the DPCCH are offset relative to the DPDCHs power by PO1, PO2 and PO3 dB respectively. The
power offsets may vary in time. USRAN may use the SSDT operation as specified in clause 5.2.2 to determine what
power offset to use for TFCI in hard split mode with respect to the associated downlink DPDCH. The method for
controlling the power offsets within USRAN is specified in TS 125 433 [6].
5.2.1.2
Ordinary transmit power control
5.2.1.2.1
UE behaviour
The UE shall generate TPC commands to control the network transmit power and send them in the TPC field of the
uplink DPCCH. An example on how to derive the TPC commands in given in clause B.2.
The UE shall check the downlink power control mode (DPC_MODE) before generating the TPC command:
-
if DPC_MODE = 0: the UE sends a unique TPC command in each slot and the TPC command generated is
transmitted in the first available TPC field in the uplink DPCCH;
-
if DPC_MODE = 1: the UE repeats the same TPC command over 3 frames and the new TPC command is
transmitted such that there is a new command at the beginning of the frame.
ETSI
24
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
The DPC_MODE parameter is a UE specific parameter controlled by the USRAN.
The UE shall not make any assumptions on how the downlink power is set by USRAN, in order to not prohibit usage of
other USRAN power control algorithms than what is defined in clause 5.2.1.2.2.
5.2.1.2.2
USRAN behaviour
Upon receiving the TPC commands USRAN shall adjust its downlink DPCCH/DPDCH power accordingly. For
DPC_MODE = 0, USRAN shall estimate the transmitted TPC command TPCest to be 0 or 1, and shall update the power
every frame. If DPC_MODE = 1, USRAN shall estimate the transmitted TPC command TPCest over three frames to be
0 or 1, and shall update the power every three frames.
After estimating the k:th TPC command, USRAN shall adjust the current downlink power P(k-1) [dB] to a new power
P(k) [dB] according to the following formula:
P(k) = P(k - 1) + PTPC(k) + Pbal(k),
where PTPC(k) is the k:th power adjustment due to the inner loop power control, and Pbal(k) [dB] is a correction
according to the downlink power control procedure for balancing radio link powers towards a common reference power.
The power balancing procedure and control of the procedure is described in TS 125 433 [6].
PTPC(k) is calculated according to the following.
If the value of Limited Power Increase Used parameter is "Not used", then
⎧+ Δ
PTPC (k ) = ⎨ TPC
⎩− Δ TPC
if TPC est (k ) = 1
, [dB].
if TPC est (k ) = 0
(1)
If the value of Limited Power Increase Used parameter is "Used", then the k:th inner loop power adjustment shall be
calculated as:
⎧+ ΔTPC
⎪
PTPC (k ) = ⎨ 0
⎪− Δ
⎩ TPC
if TPC est (k ) = 1 and Δ sum (k ) + Δ TPC < Power_Raise_Limit
if TPC est (k ) = 1 and Δ sum (k ) + Δ TPC ≥ Power_Raise_Limit , [dB]
if TPC est (k ) = 0
(2)
where
k −1
Δ sum (k ) =
P
(i )
∑
DL_Power_Averaging_Window_Size
TPC
i =k −
is the temporary sum of the last DL_Power_Averaging_Window_Size inner loop power adjustments (in dB).
For the first (DL_Power_Averaging_Window_Size - 1) adjustments after the activation of the limited power increase
method, formula (1) shall be used instead of formula (2). Power_Raise_Limit and DL_Power_Averaging_Window_Size
are parameters configured in the USRAN.
The power control step size ΔTPC can take four values: 0,5 dB, 1 dB, 1,5 dB or 2 dB. It is mandatory for USRAN to
support ΔTPC of 1 dB, while support of other step sizes is optional.
In addition to the above described formulas on how the downlink power is updated, the restrictions below apply.
In case of congestion (commanded power not available), USRAN may disregard the TPC commands from the UE.
The average power of transmitted DPDCH symbols over one timeslot shall not exceed Maximum_DL_Power (dB), nor
shall it be below Minimum_DL_Power (dB). Transmitted DPDCH symbol means here a complex QPSK symbol before
spreading which does not contain DTX. Maximum_DL_Power (dB) and Minimum_DL_Power (dB) are power limits
for one channelization code, relative to the primary CPICH power TS 125 433 [6].
ETSI
25
5.2.1.3
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Power control in compressed mode
The aim of downlink power control in uplink or/and downlink compressed mode is to recover as fast as possible a
signal-to-interference ratio (SIR) close to the target SIR after each transmission gap.
The UE behaviour is the same in compressed mode as in normal mode, described in clause 5.2.1.2, except that the target
SIR is offset by higher layer signalling. However due to transmission gaps in uplink compressed frames there may be
incomplete sets of TPC commands when DPC_MODE = 1.
USRAN behaviour is as stated in clause 5.2.1.2.2 except for DPC_MODE = 1 where missing TPC commands in the UL
may lead the USRAN to changing its power more frequently than every 3 slots.
In compressed mode, compressed frames may occur in either the uplink or the downlink or both. In compressed frames,
the transmission of downlink DPDCH(s) and DPCCH shall be stopped during transmission gaps.
The power of the DPCCH and DPDCH in the first slot after the transmission gap should be set to the same value as in
the slot just before the transmission gap.
During compressed mode except during downlink transmission gaps, USRAN shall estimate the k:th TPC command
and adjust the current downlink power P(k - 1) [dB] to a new power P(k) [dB] according to the following formula:
P(k) = P(k - 1) + PTPC(k) + PSIR(k) + Pbal(k),
where PTPC(k) is the k:th power adjustment due to the inner loop power control, PSIR(k) is the k-th power adjustment
due to the downlink target SIR variation, and Pbal(k) [dB] is a correction according to the downlink power control
procedure for balancing radio link powers towards a common reference power. The power balancing procedure and
control of the procedure is described in TS 125 433 [6].
Due to transmission gaps in uplink compressed frames, there may be missing TPC commands in the uplink.
For DPC_MODE = 0 if no uplink TPC command is received, PTPC(k) derived by the satellite gateway shall be set to
zero. Otherwise, PTPC(k) is calculated the same way as in normal mode (see clause 5.2.1.2.2) but with a step size ΔSTEP
instead of ΔTPC.
For DPC_MODE = 1, the sets of slots over which the TPC commands are processed shall remain aligned to the frame
boundaries in the compressed frame. If this results in an incomplete set of TPC commands, the UE shall transmit the
same TPC commands in all slots of the incomplete set.
The power control step size ΔSTEP = ΔRP-TPC during RPL slots after each transmission gap and ΔSTEP = ΔTPC
otherwise, where:
-
RPL is the recovery period length and is expressed as a number of slots. RPL is equal to the minimum value
out of the transmission gap length and 7 slots. If a transmission gap is scheduled to start before RPL slots have
elapsed, then the recovery period shall end at the start of the gap, and the value of RPL shall be reduced
accordingly.
-
ΔRP-TPC is called the recovery power control step size and is expressed in dB. ΔRP-TPC is equal to the
minimum value of 3 dB and 2ΔTPC.
The power offset PSIR(k) = δPcurr - δPprev, where δPcurr and δPprev are respectively the value of δP in the current slot
and the most recently transmitted slot and δP is computed as follows:
δP = max (ΔP1_compression, …, ΔPn_compression) + ΔP1_coding + ΔP2_coding
where n is the number of different TTI lengths amongst TTIs of all TrChs of the CCTrCh, where ΔP1_coding and
ΔP2_coding are computed from uplink parameters DeltaSIR1, DeltaSIR2, DeltaSIRafter1, DeltaSIRafter2 signalled by
higher layers as:
-
ΔP1_coding = DeltaSIR1 if the start of the first transmission gap in the transmission gap pattern is within the
current frame.
ETSI
26
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
-
ΔP1coding = DeltaSIRafter1 if the current frame just follows a frame containing the start of the first
transmission gap in the transmission gap pattern.
-
ΔP2_coding = DeltaSIR2 if the start of the second transmission gap in the transmission gap pattern is within
the current frame.
-
ΔP2_coding = DeltaSIRafter2 if the current frame just follows a frame containing the start of the second
transmission gap in the transmission gap pattern.
-
ΔP1_coding = 0 dB and ΔP2_coding = 0 dB in all other cases.
and ΔPi_compression is defined by:
-
ΔPi_compression = 3 dB for downlink frames compressed by reducing the spreading factor by 2.
-
ΔPi_compression = 10 log (15 × Fi / (15 × Fi - TGLi)) if there is a transmission gap created by puncturing
method within the current TTI of length Fi frames, where TGLi is the gap length in number of slots (either
from one gap or a sum of gaps) in the current TTI of length Fi frames.
-
ΔPi_compression = 0 dB in all other cases.
In case several compressed mode patterns are used simultaneously, a δP offset is computed for each compressed mode
pattern and the sum of all δP offsets is applied to the frame.
For all time slots except those in transmissions gaps, the average power of transmitted DPDCH symbols over one
timeslot shall not exceed Maximum_DL_Power (dB) by more than δPcurr, nor shall it be below Minimum_DL_Power
(dB). Transmitted DPDCH symbol means here a complex QPSK symbol before spreading which does not contain DTX.
Maximum_DL_Power (dB) and Minimum_DL_Power (dB) are power limits for one channelization code, relative to the
primary CPICH power TS 125 433 [6].
5.2.1.4
Spot selection diversity transmit power control
5.2.1.4.1
General
Spot Selection Diversity Transmit power control (SSDT) is another macro diversity method in soft handover mode.
This method is optional in USRAN.
Operation is summarized as follows. The UE selects one of the spots from its active set to be "primary", all other spots
are classed as "non-primary". The main objective is to transmit on the downlink from the primary spot, thus reducing
the interference caused by multiple transmissions in a soft handover mode. A second objective is to achieve fast spot
selection without network intervention, thus maintaining the advantage of the soft handover. In order to select a primary
spot, each spot is assigned a temporary IDentification (ID) and UE periodically informs a primary spot ID to the
connecting spots. The non-primary spots selected by UE switch off the transmission power. The primary spot ID is
delivered by UE to the active spots via uplink FBI field. SSDT activation, SSDT termination and ID assignment are all
carried out by higher layer signalling.
SSDT is only supported when the P-CPICH is used as the downlink phase reference.
5.2.1.4.1.1
Definition of temporary spot identification
Each spot is given a temporary ID during SSDT and the ID is utilized as site selection signal. The ID is given a binary
bit sequence. There are three different lengths of coded ID available denoted as "long", "medium" and "short". The
network decides which length of coded ID is used. Settings of ID codes for 1-bit and 2-bit FBI are exhibited in tables 4
and 5, respectively.
ETSI
27
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Table 4: Settings of ID codes for 1 bit FBI
ID label
a
b
c
d
e
f
g
h
ID code
"medium"
(0)0000000
(0)1010101
(0)0110011
(0)1100110
(0)0001111
(0)1011010
(0)0111100
(0)1101001
"long"
000000000000000
101010101010101
011001100110011
110011001100110
000111100001111
101101001011010
011110000111100
110100101101001
"short"
00000
01001
11011
10010
00111
01110
11100
10101
Table 5: Settings of ID codes for 2 bit FBI
ID label
a
b
c
d
e
f
g
h
ID code
(Column and Row denote slot position and FBI-bit position)
"long"
"medium"
"short"
(0)0000000
(0)000
000
(0)0000000
(0)000
000
(0)0000000
(0)000
000
(1)1111111
(1)111
111
(0)1010101
(0)101
101
(0)1010101
(0)101
101
(0)1010101
(0)101
101
(1)0101010
(1)010
010
(0)0110011
(0)011
011
(0)0110011
(0)011
011
(0)0110011
(0)011
011
(1)1001100
(1)100
100
(0)1100110
(0)110
110
(0)1100110
(0)110
110
(0)1100110
(0)110
110
(1)0011001
(1)001
001
The ID code bits shown in tables 4 and 5 are transmitted from left to right. In table 5, the first row gives the first FBI bit
in each slot, the second row gives the 2nd FBI bit in each slot. The ID code(s) are transmitted aligned to the radio frame
structure (i.e. ID codes shall be terminated within a frame). If FBI space for sending the last ID code within a frame
cannot be obtained, the first bit(s) from that ID code are punctured. The bit(s) to be punctured are shown in brackets in
tables 4 and 5.
The alignment of the ID codes to the radio frame structure is not affected by transmission gaps resulting from uplink
compressed mode.
5.2.1.4.2
TPC procedure in UE
The UE shall generate TPC commands to control the satellite transmit power and send them in the TPC field of the
uplink DPCCH based on the downlink signals from the primary spot as selected by the UE. An example on how to
derive the TPC commands is given in clause B.2.
5.2.1.4.3
Selection of primary spot
The UE selects a primary spot periodically by measuring the RSCP of P-CPICHs transmitted by the active spots. The
spot with the highest P-CPICH RSCP is detected as a primary spot.
5.2.1.4.4
Delivery of primary spot ID
The UE periodically sends the ID code of the primary spot via portion of the uplink FBI field assigned for SSDT use
(FBI S field). A spot recognizes its state as non-primary if the following conditions are fulfilled simultaneously:
-
The received ID code does not match with the own ID code.
ETSI
28
-
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
The received uplink signal quality satisfies the following:
SIRestIDcode > SIRtarget + Qth [dB]
Where SIRestIDcode is the average of estimated signal-to-interference ratio of the received uplink DPCH
SIRest, described in clause 5.1.2.2.1, over the uplink slots containing the received spot ID code; SIRtarget
is the target SIR of the uplink, described in clause 5.1.2.2.1; and Qth is uplink quality threshold which
corresponds to the uplink DPCH quality level relative to the SIRtarget. Qth parameter is signalled via
higher layer signalling.
-
If uplink compressed mode is used, and less than ⎣NID/3⎦ bits are lost from the ID code (as a result of uplink
compressed mode), where NID is the number of bits in the ID code (after puncturing according to
clause 5.2.1.4.1.1, if puncturing has been done).
Otherwise the spot recognizes its state as primary.
The state of the spots (primary or non-primary) in the active set is updated synchronously. If a spot receives the last
portion of the coded ID in uplink slot j, the state of spot is updated in downlink slot (j + 1 + Tos) mod 15, where Tos is
defined as a constant of 2 time slots. The updating of the spot state is not influenced by the operation of downlink
compressed mode.
At the UE, the primary ID code to be sent to the spots is segmented into a number of portions. These portions are
distributed in the uplink FBI S-field. The spot in SSDT collects the distributed portions of the primary ID code and then
detects the transmitted ID. The period of the primary spot update depends on the settings of the code length and the
number of FBI bits assigned for SSDT use as shown in table 6. However, SSDT is only applicable with
DPC_MODE = 0.
Table 6: Period of primary spot update
code length
"long"
"medium"
"short"
5.2.1.4.5
The number of FBI bits per slot assigned for SSDT
1
2
1 update per frame
2 updates per frame
2 updates per frame
4 updates per frame
3 updates per frame
5 updates per frame
TPC procedure in the network
In SSDT, a non-primary spot can switch off its DPDCH output (i.e. no transmissions).
The spot manages two downlink transmission power levels, P1, and P2. Power level P1 is used for downlink DPCCH
transmission power level and this level is updated in the same way with the downlink DPCCH power adjustment
specified in clauses 5.2.1.2.2 (for normal mode) and 5.2.1.3 (for compressed mode) regardless of the selected state
(primary or non-primary). The actual transmission power of TFCI, TPC and pilot fields of DPCCH is set by adding P1
and the offsets PO1, PO2 and PO3, respectively, as specified in clause 5.2.1.1. P2 is used for downlink DPDCH
transmission power level and this level is set to P1 if the spot is selected as primary, otherwise P2 is switched off. The
spot updates P1 first and P2 next, and then the two power settings P1 and P2 are maintained within the power control
dynamic range. Table 7 summarizes the updating method of P1 and P2.
Table 7: Updating of P1 and P2
State of spot
non-primary
primary
P1 (DPCCH)
P2 (DPDCH)
Updated in the same way
Switched off
with the downlink DPCCH
power adjustment specified
in clauses 5.2.1.2.2
and 5.2.1.3.
= P1
ETSI
29
5.2.1.5
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Open Loop power control
Open loop power control can be activated continuously after DPCCH/DPDCH link establishment. This is configured by
higher layers (RRC).
5.2.2
AICH
The UE is informed about the relative transmit power of the AICH (measured as the power per transmitted acquisition
indicator) compared to the primary CPICH transmit power by the higher layers.
5.2.3
PICH
The UE is informed about the relative transmit power of the PICH (measured as the power over the paging indicators)
compared to the primary CPICH transmit power by the higher layers.
5.2.4
S-CCPCH
The TFCI and pilot fields may be offset relative to the power of the data field. The power offsets may vary in time.
5.2.5
MICH
The UE is informed about the relative transmit power of the MICH (measured as the power over the notification
indicators) compared to the primary CPICH transmit power by the higher layers.
6
Random access procedure
6.1
Physical random access procedure
The physical random access procedure described in this clause is initiated upon request from the MAC sublayer.
Before the physical random-access procedure can be initiated, Layer 1 shall receive the following information from the
higher layers (RRC):
-
The preamble scrambling code.
-
The message length in time, either 10 ms or 20 ms.
-
The AICH_Transmission_Timing parameter [0 or 1].
-
The set of available signatures and the set of available RACH sub-channels for each Access Service Class
(ASC). Sub-channels are defined in clause 6.1.1.
-
The power-ramping factor Power Ramp Step [integer > 0].
-
The parameter Preamble Retrans Max [integer > 0].
-
The initial preamble power Preamble_Initial_Power.
-
The Power offset P p-m = Pmessage-control - Ppreamble, measured in dB, between the power of the last transmitted
preamble and the control part of the random-access message.
-
The set of Transport Format parameters. This includes the power offset between the data part and the control
part of the random-access message for each Transport Format.
Note that the above parameters may be updated from higher layers before each physical random access procedure is
initiated.
ETSI
30
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
At each initiation of the physical random access procedure, Layer 1 shall receive the following information from the
higher layers (MAC):
-
The Transport Format to be used for the PRACH message part.
-
The ASC of the PRACH transmission.
-
The data to be transmitted (Transport Block Set).
The physical random-access procedure shall be performed as follows:
1)
Derive the available uplink access slots, in the next full access slot set, for the set of available RACH
sub-channels within the given ASC with the help of clauses 6.1.1 and 6.1.2. Randomly select one access slot
among the ones previously determined. If there is no access slot available in the selected set, randomly select
one uplink access slot corresponding to the set of available RACH sub-channels within the given ASC from
the next access slot set. The random function shall be such that each of the allowed selections is chosen with
equal probability.
2)
Randomly select a signature from the set of available signatures within the given ASC. The random function
shall be such that each of the allowed selections is chosen with equal probability.
3)
Set the Preamble Retransmission Counter to Preamble Retrans Max.
4)
Set the parameter Commanded Preamble Power to Preamble_Initial_Power.
5)
In the case that the Commanded Preamble Power exceeds the maximum allowed value, set the preamble
transmission power to the maximum allowed power. In the case that the Commanded Preamble Power is
below the minimum level required in TS 125 101 [7], set the preamble transmission power to a value, which
shall be at or above the Commanded Preamble Power and at or below the required minimum power specified
in TS 125 101 [7]. Otherwise set the preamble transmission power to the Commanded Preamble Power.
Transmit a preamble using the selected uplink access slot, signature, and preamble transmission power.
6)
If no positive or negative acquisition indicator (AI ≠ + 1 nor - 1) corresponding to the selected signature is
detected in the downlink access slot corresponding to the selected uplink access slot:
6.1) Select the next available access slot in the set of available RACH sub-channels within the given ASC.
6.2) Randomly select a new signature from the set of available signatures within the given ASC. The random
function shall be such that each of the allowed selections is chosen with equal probability.
6.3) Increase the Commanded Preamble Power by ΔP0 = Power Ramp Step [dB]. If the Commanded
Preamble Power exceeds the maximum allowed power by 6dB, the UE may pass L1 status ("No ack on
AICH") to the higher layers (MAC) and exit the physical random access procedure.
6.4) Decrease the Preamble Retransmission Counter by one.
6.5) If the Preamble Retransmission Counter > 0 then repeat from step 5. Otherwise pass L1 status ("No ack
on AICH") to the higher layers (MAC) and exit the physical random access procedure.
7)
If a negative acquisition indicator corresponding to the selected signature is detected in the downlink access
slot corresponding to the selected uplink access slot, pass L1 status ("Nack on AICH received") to the higher
layers (MAC) and exit the physical random access procedure.
8)
Transmit the random access message three or four uplink access slots after the uplink access slot of the last
transmitted preamble depending on the AICH transmission timing parameter. Transmission power of the
control part of the random access message should be P p-m [dB] higher than the power of the last transmitted
preamble. Transmission power of the data part of the random access message is set according to clause 5.1.1.2.
9)
Pass L1 status "RACH message transmitted" to the higher layers and exit the physical random access
procedure.
ETSI
31
6.1.1
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
RACH sub-channels
A RACH sub-channel defines a sub-set of the total set of uplink access slots. There are a total of 12 RACH
sub-channels. RACH sub-channel #i (i = 0, …, 11) consists of the following uplink access slots:
-
Uplink access slot #i leading by τp-a chips the downlink access slot #i contained within the 10 ms interval that
is time aligned with P-CCPCH frames for which SFN mod 8 = 0 or SFN mod 8 = 1.
-
Every 12th access slot relative to this access slot.
The access slots of different RACH sub-channels are also illustrated in table 8.
Table 8: The available uplink access slots for different RACH sub-channels
SFN modulo 8 of
corresponding
P-CCPCH frame
0
1
2
3
4
5
6
7
6.1.2
Sub-channel number
0
1
2
3
4
5
6
7
0
12
1
13
2
14
3
4
5
6
7
0
12
1
13
2
14
3
9
6
10
7
3
4
11
8
5
9
6
10
7
8
9
10
11
8
5
9
6
10
7
11
4
1
13
2
14
3
4
8
5
11
0
12
8
9
10
11
0
12
1
13
2
14
RACH access slot sets
The PRACH contains two sets of access slots as shown in figure 2. Access slot set 1 contains PRACH slots 0 - 7 and
starts τp-a chips before the downlink P-CCPCH frame for which SFN mod 2 = 0. Access slot set 2 contains PRACH
slots 8 - 14 and starts (τp-a - 2 560) chips before the downlink P-CCPCH frame for which SFN mod 2 = 1.
AICH access
slots
SFN mod 2 = 0
τp-a
#0
PRACH
access slots
#0
#1
#2
#1
#3
#2
#4
#3
#5
#4
#6
SFN mod 2 = 1
#5
#7
Access slot set 1
#6
#8
#7
#9
#8
#9
#10
#11
#10
#11
#12
#13
#12
#14
Access slot set 2
10 ms
10 ms
Figure 2: PRACH access slot and downlink AICH relation (τp-a = 7 680 chips)
ETSI
#13
#14
32
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Annex A (informative):
Power control
A.1
Downlink power control timing
The power control timing described in this annex should be seen as an example on how the control bits have to be
placed in order to permit a short TPC delay.
In order to maximize the spot radius distance within which one-slot control delay is achieved, the frame timing of an
uplink DPCH is delayed by 1 024 chips from that of the corresponding downlink DPCH measured at the UE antenna.
Responding to a downlink TPC command, the UE shall change its uplink DPCH output power at the beginning of the
first uplink pilot field after the TPC command reception. Responding to an uplink TPC command, the USRAN access
point shall change its DPCH output power at the beginning of the next downlink pilot field after the reception of the
whole TPC command. Note that in soft handover, the TPC command is sent over one frame when DPC_MODE is 0 and
over three frames when DPC_MODE is 1. Note also that the delay from the uplink TPC command reception to the
power change timing is not specified for USRAN. The UE shall decide and send TPC commands on the uplink based on
the downlink SIR measurement. The TPC command field on the uplink starts, when measured at the UE antenna,
512 chips after the end of the downlink pilot field. The USRAN access point shall decide and send TPC commands
based on the uplink SIR measurement. However, the SIR measurement periods are not specified either for UE nor
USRAN.
Figure A.1 illustrates an example of transmitter power control timings.
Slot (2 560 chips)
DL DPCCH
at USRAN
PILOT
T TF
P
C CI
Data1
Data2
Propagation delay
DL-UL timing
offset (1 024 chips)
DL DPCCH
at UE
PILOT
Data1
PILOT
Data1
T
P
C
Response
To TPC (see note 2)
T TF
P
C CI
Data2
PILOT
Data1
T
P
C
512 chips
DL SIR
Measurement
(see note 1)
UL DPCCH
at UE
PILOT
Response
to TPC
TFCI
TPC
PILOT
Slot (2 560 chips)
UL SIR
Measurement
(see note 1)
Propagation delay
UL DPCCH
at USRAN
PILOT
TFCI
TPC
PILOT
NOTE 1: The SIR measurement periods illustrated here are examples. Other ways of measure are allowed to
achieve accurate SIR estimation.
NOTE 2: If there is not enough time foe USRAN to respond to the TPC, the action can be delayed until next frame.
Figure A.1: Transmitter power control timing
ETSI
33
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Annex B (informative):
Spot search procedure
During the spot search, the UE searches for a spot and determines the downlink scrambling code and frame
synchronization of that spot. The spot search is typically carried out in three steps.
Step 1: Slot synchronization
During the first step of the spot search procedure the UE uses the SCH's primary synchronization code to acquire slot
synchronization to a spot. This is typically done with a single matched filter (or any similar device) matched to the
primary synchronization code which is common to all spots. The slot timing of the spot can be obtained by detecting
peaks in the matched filter output.
Step 2: Frame synchronization and code-group identification
During the second step of the spot search procedure, the UE uses the SCH's secondary synchronization code to find
frame synchronization and identify the code group of the spot found in the first step. This is done by correlating the
received signal with all possible secondary synchronization code sequences, and identifying the maximum correlation
value. Since the cyclic shifts of the sequences are unique the code group as well as the frame synchronization is
determined.
Step 3: Scrambling-code identification
During the third and last step of the spot search procedure, the UE determines the exact primary scrambling code used
by the found spot. The primary scrambling code is typically identified through symbol-by-symbol correlation over the
CPICH with all codes within the code group identified in the second step. After the primary scrambling code has been
identified, the Primary CCPCH can be detected and the system- and spot specific BCH information can be read.
If the UE has received information about which scrambling codes to search for, steps 2 and 3 above can be simplified.
ETSI
34
ETSI TS 101 851-4-1 V2.1.1 (2008-01)
Annex C (informative):
Bibliography
ETSI TS 125 321: "Universal Mobile Telecommunications System (UMTS); Medium Access Control (MAC) protocol
specification (3GPP TS 25.321)".
ETSI TS 125 306: "Universal Mobile Telecommunications System (UMTS); UE Radio Access capabilities
(3GPP TS 25.306)".
ETSI
35
History
Document history
V1.1.1
December 2000
Publication as TS 101 851-4
V1.2.1
January 2006
Publication as TS 101 851-4
V2.1.1
January 2008
Publication
ETSI
ETSI TS 101 851-4-1 V2.1.1 (2008-01)